Various websites can elicit thousands of user comments about a business, product, news article, or other content. It can be very difficult to categorize the user comments or otherwise extract useful information from the user comments. Some websites attempt to address this problem by requesting structured input along with a comment or instead of a comment. For example, websites that host reviews can ask the reviewers to rate the business on a scale, such as one to five stars. The average of the ratings represents the people's opinions about the venue. Some websites ask the reviewers to rate individual aspects (such as the food, the service, etc.) of a business. The individual aspects, however, need to be predefined according to the type of venue or product reviewed (e.g., noise for hotels, food quality/taste for restaurants, and ease of use for electronic devices). Accordingly, use of structured data to develop a summary of user sentiment is limited by the structure. Unstructured comments, such as those typically posted in association with a news article, remain difficult to categorize.